INFLUENCE OF AGING ON VITAMIN-D METABOLISM

Aging is associated both with calcium deficiency, due to low dietary i ntake and decreased intestinal absorption, and with vitamin D deficien cy, secondary to depletion of body stores resulting from inadequate ex posure to sunlight. Hepatic hydroxylation of vitamin D remains normal in elderly individuals. Recent data suggest that renal hydroxylation o f vitamin D, previously believed to decrease with advancing age, also remains virtually normal even when creatinine clearance declines, as i s very often the case in elderly patients. The combined deficiency in calcium and vitamin D stimulates the secretion of parathyroid hormone which tends to normalize serum calcium levels and causes the bone diso rders of senile osteoporosis.